Catenanes and Rotaxanes

Question 1

What is a catenane?

Answer 1

Two or more rings that are interlocked and cannot be separated without breaking a bond

Question 2

What is a rotaxane?

Answer 2

Long, linear molecule threaded through a macrocyclic ring.

Question 3

What is a pseudorotaxane?

Answer 3

Rotaxanes without bulky groups on the end

Question 4

What are the methods of forming catenanes?

Answer 4

Clipping
Double clipping
Magic ring

Question 5

What are the methods of forming rotaxanes?

Answer 5

Clipping
Stoppering
Slippage
Swelling
Magic ring/rod

Question 6

What is Grubbs Catalyst?

Answer 6

DIAGRAM

Question 7

What is the mechanism for ring-closing metathesis?

Answer 7

DIAGRAM

Question 8

Why is ring-closing metathesis ran under nitrogen?

Answer 8

To take the reaction to completion

Question 9

What other coordination geometries can there be?

Answer 9

Ru(II) - octahedral
Zn(II) - 5 donor atoms
Pd(II) - square planar
Au(I) - linear

Question 10

What templates can be used in direction self-assembly?

Answer 10

Metal cations
Pi-pi stacking
Hydrogen bonding

Question 11

What is active metal template synthesis?

Answer 11

DIAGRAM

Question 12

What is the mechanism of triazole formation?

Answer 12

DIAGRAM

Question 13

What is a copper click reaction?

Answer 13

DIAGRAM

Question 14

Why is active metal templation useful?

Answer 14

1) Requires only catalytic amounts of expensive metal cation template
2) Can generate interlocked components which do not possess ligating functionality - more versatility in future applications

Question 15

What is a trefoil knot?

Answer 15

A single strand which intertwines itself with three crossing points

Question 16

What are the two molecular level motions?

Answer 16

Pirouetting

Shuttling

Question 17

What is a molecular shuttle?

Answer 17

Macrocyclic component resides at each station for 50% of the time (in solution), and both sites are identical

Question 18

What evidence is there for molecular shuttles?

Answer 18

At low temperature - two sets of peaks in H NMR for hydroquinone protons
At high temperatures - fast exchange so NMR sees an average - like hydroquinone protons are identical

Question 19

What stimuli can molecular switches have?

Answer 19

pH

Electrochemical (REDOX)

Question 20

What is the difference between molecular switches and molecular motors?

Answer 20

Switches - unable to do work, the task performed is undone by resetting the switch
Motors - able to do work. The key to this is directionality